Background: Bariatric surgical procedures are becoming increasingly common and can lead to significant long-term weight loss in properly motivated patients. However, it is less clear whether these procedures improve health outcomes. Observational studies have had conflicting conclusions about the effect of general weight loss on cardiovascular mortality, although the American Cancer Society has reported decreased mortality rates with intentional weight loss. Several retrospective cohort studies have also reported decreased mortality rates in patients who have lost weight after bariatric surgery. Sjöström and colleagues examined the effects of different bariatric surgery techniques on long-term survival.

The Study: The prospective, matched, controlled trial included 4,047 persons who were obese. Approximately one half of participants received one of several bariatric surgeries (i.e., gastric bypass, gastric banding, or vertical banded gastroplasty). Patients in the control group were eligible to receive non-surgical treatment. Participants were 37 to 60 years of age and had a minimum body mass index (BMI) of 34 kg per m² for men and 38 kg per m² for women. Patients with comorbidities (e.g., diabetes, hypertension, hyperlipidemia, myocardial infarction or stroke that occurred more than six months before the study) were eligible unless they were not candidates for surgery. Mortality rates and causes of death were tracked during the study by cross-referencing population records with death certificates.

Results: Analysis included 2,010 patients in the surgical group and 2,037 in the control group; the mean follow-up period was 10.9 years. The baseline characteristics of both groups were similar, although patients in the surgical group were an average of 5 lb (2.3 kg) heavier and were more likely to be smokers than those in the control group. In the surgical group, 1,369 patients received vertical banded gastroplasty, 376 received gastric banding, and 265 received gastric bypass surgery.

Overall, patients in the control group remained at their baseline weight during the observation period, whereas those in the surgical group maintained significant weight loss during the postsurgery observation period (see accompanying table).

Although mortality rates were low in both groups during the follow-up period, they were lower in the surgical group (101 deaths [5.0 percent]) than in the control group (129 deaths [6.3 percent]). The surgical group had an unadjusted hazard ratio for overall mortality of 0.76 compared with the control group; this decreased to 0.71 after adjusting for sex, age, and risk factors. There were no significant interactions between study group and sex, diabetes, BMI, age, or history of cardiac disease. There was no significant difference in cardiovascular mortality between the two groups.

Conclusion: Although the study was not sufficiently powered to compare the effects of different bariatric surgery techniques, surgery was associated with long-term weight loss and significantly reduced mortality rates. Because other studies, such as the Framingham and Manitoba studies, showed that obesity was the only significant predictor of mortality after 26 years, the effects of bariatric surgery on survival might be even more dramatic in longer-term studies.

editor's note: Family physicians are increasingly caring for patients who have already undergone or are candidates for bariatric surgery because of obesity; therefore, family physicians are uniquely positioned to help counsel patients about whether bariatric surgery is a viable option. There are specific guidelines that can help physicians determine whether a patient is eligible for bariatric surgery.¹

This study provides a much-needed perspective on the potential benefits of weight reduction in obese patients, but it was not sufficiently powered to attribute specific reasons for reduced mortality.

A recent retrospective study examining the long-term outcomes after gastric bypass surgery reported similar results, with a 40 percent reduction in overall mortality after seven years, including from cardiovascular causes and cancer. However, other causes of death such as accidents and suicide increased by 58 percent in the surgical group compared with the control group.^2,3 Physicians should be aware that bariatric surgery can lead to serious complications in up to 10 percent of patients.¹—k.t.m.